Speech Disruptions in the Narratives of English-Speaking Children ...

seven age levels (i.e., from kindergarten to high school
seniors). In general, younger age groups tended to produce
more silent pauses and longer silent pause duration
(measured by silent pause length per syllable) than
older age groups. It was suggested that younger children
needed more time for planning language production than
older age groups.
Wijnen (1990) analyzed the frequency and distribution
of speech disruptions in a typically developing Dutch
child between the ages of 2;4 (years;months) and 2;11.
The frequency of speech disruptions increased initially
and then subsequently declined. In addition, speech disruptions
were randomly distributed within sentences at
the first half of the observation period but tended to concentrate
at phrase boundaries or sentence boundaries at
the second half. Wijnen concluded that the decrease of
speech disruptions was related to the abundant use of a
few syntactic frames (e.g., Pronoun + Verb + X ) as grammar
developed. The frequent use led to an increase of
automaticity of these frames in sentence formulation
and reduced the risk of disruptions (Wijnen). In addition,
speech disruptions were concentrated at phrase and sentence
boundaries because these were the locations where
language planning took place, which reflected the emergence
of a sentence formulation system in this child.
Colburn and Mysak (1982) examined the semantic–
syntactic structures (e.g., locative + action, wh-question)
of dysfluent utterances in longitudinal samples of 4 children
from MLU Level I–IV. Novel semantic–syntactic
structures that were just emerging provoked more dysfluencies
than the structures that had recently emerged
or were consistently used in the child’s language sample.
Colburn and Mysak concluded that novel structures
tended to precipitate dysfluencies because these structures
were not fully practiced and hence placed high
linguistic stress in sentence formulation.
Rispoli and Hadley (2001) investigated the relationship
between speech disruptions, sentence length, and
complexity in children from 2;6 to 4;0 years. Their results
indicated that dysfluent sentences tended to be
longer and more complex than fluent ones. With the development
of the child’s grammar, the gap in complexity
between the dysfluent and fluent sentences expanded
even when length effect was partialed out. Rispoli and
Hadley (2001) therefore argued that as grammatical development
proceeded, speech disruptions tended to appear
in more-complex sentences. When a higher level of
sentence complexity emerged, the sentence production
mechanism was slow and inefficient, triggering a high
rate of speech disruptions. With development, complex
sentences became more automatic, triggering speech disruption
less often. In a similar vein, Rispoli and Hadley
(2005) conducted a longitudinal study to investigate
the relationship between speech disruptions and the
acquisition of tense and agreement markers (i.e., third
person singular –s, past tense –ed, and copula BE). The
results showed that the disruption rate in sentences with
tense and agreement markers decreased as the child’s
productive level of these markers (Hadley & Short, 2005)
increased. It was again argued that the decrease in disruptions
in sentences with tense and agreement markers
wasrelatedtotheincreaseinautomaticityofthose
markers.
In summary, evidence from typically developing children
suggests that speech disruptions decrease with syntactic
development. An increase in the automaticity of
syntactic knowledge may reduce the risk of disruptions.
Although not addressed in these studies, lexical development
may also play a role in speech disruptions. Evidence
from adult language production shows that some
speech disruptions stem from problems in lexical retrieval
(Levelt, 1989; Maclay & Osgood, 1959). The ability
to retrieve lexical items is related to the depth of
knowledge in the semantic lexicon (McGregor, Newman,
Reilly, & Capone, 2002). As the degree of semantic knowledge
becomes enriched, children are able to retrieve lexical
items more easily and efficiently, and disruptions
due to difficulty in lexical retrieval may decrease. We
therefore make the assumption that the production of
speech disruptions in developmental language is related
to general language ability (i.e., strength of linguistic
representations), including lexical and syntactic abilities.
Two questions arise here: How are sentences produced
from a representation of linguistic and nonlinguistic
knowledge, and how do weak linguistic representations
result in disruptions in language production To
answer these questions, we need to consider how preverbal
messages are grammatically encoded (Bock &
Levelt, 1994; Levelt, 1989). When a speaker intends to
express a message such as Theboyeatsthecakes,he
first builds up a nonlinguistic representation of this
message. The preverbal message is then translated into
linguistic forms by grammatical encoding. At grammatical
encoding, the speaker needs to retrieve lemmas from
the lexicon, code specific information for these lemmas
(e.g., definiteness for boy; person, number and tense for
eat), and assign them syntactic functions (e.g., subject,
main verb). The information of lemmas and their syntactic
functions, in turn, guides the activation of syntactic
frames or phrase structures for positioning these
lemmas (Bock & Levelt, 1994). For instance, a syntactic
frame with the definite article the is built up for the
lemma boy and is located at the subject position in a sentence
because the lemma boy is attached with a feature
of definiteness and is assigned the syntactic function of
subject. It should be noted that this model (Bock & Levelt,
1994; Levelt, 1989) permits incremental production—
that is, a sentence can be processed in increments or
724 Journal of Speech, Language, and Hearing Research • Vol. 51 • 722–738 • June 2008
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